1. Field of the Invention
The present invention is in the field of etching silicon carbide by plasma etching with a mixture of halogenated hydrocarbon and relatively high amounts of oxygen.
2. DESCRIPTION OF THE PRIOR ART
As is known, silicon carbide is suitable for use as a semiconductor for blue-colored light-emitting diodes. The use of silicon carbide for microcomponents, for example, for field effect transistors or semiconductor sensors is met with technological difficulties. Although liquid-phase epitaxy is possible with high dopings at high temperatures, it is not well suited for low dopings in the range from about 10.sup.16 cm.sup.-3 to 10.sup.17 cm.sup.-3 at room temperatures. Unlike many other semiconductors, there is no complete dissociation at room temperature, and the imperfection concentrations are also correspondingly higher at higher temperatures. Planar technology cannot be used without modification because the diffusion temperature of about 2000.degree. C. is relatively high and the risk of decomposing the surface layers as well as the materials transport in transport reactions is very possible at these temperatures. Moreover, the covering of silicon oxide or silicon dioxide usually employed for structuring in such planar technology is not suitable at these temperatures (see the article by Kurzinger in Solid State Electronics, Vol. 21, page 1129). Although a plurality of blue-light diodes can be manufactured as mesa structures and later severed with a diamond saw, these structures are likewise manufactured at a relatively high temperature above 1000.degree. C. with a gas etchant which contains chlorine and a small proportion of oxygen. (See the aforementioned article in "Solid State Electronics", pages 1129-1132).
It is known that a plasma etching of amorphous silicon carbide can be performed in a gas mixture of carbon tetrafluoride CF.sub.4 and oxygen O.sub.2 (J. Electrochem. Soc., Solid-State Sc. and Techn., February 1985, pages 418-422).